With Positive Material Identification (PMI) the alloy composition, and thus the identity of materials, can be determined.
If a material certificate is missing and/or you need to be certain about the type of material used, PMI as a NDT method is the best solution.
Positive Material Identification is particularly useful for high-quality metals like stainless steel and high alloy metals.
MIT offers X-Ray Fluorescence (XRF) as one of the methods for PMI. The equipment contains radioactive sources or a low voltage x-ray generator, which sends out radiation. The exposed material then temporarily sends element-specific radiation back, generating energy. As every element has its own atomic structure, this reflection will generate a different energy level for every element.
This energy is measured and detected, thus identifying the alloy elements. The disengaged radiation is very low and extra safety means are not necessary.
The important advantage of the XRF-method is that, in service, it can be executed without damaging the material, and the results are received immediatlely after inspection.